After replacing a tore up Flex pipe my does not accelerate

Welcome to 2CarPros. Your description sounds like the exhaust is plugged partly, likely by pieces of the flex pipe as it came apart. A quick way to test this would be to disconnect the Y pipe at the rear connection and see if the power returns. If it does you will likely need to check the converter and see if it's plugged or seriously restricted. You might be able to remove it and blow the restriction out if it is something like pieces of rust. I doubt it is farther back although it could be in the muffler if it was driven a while, that is because the exhaust heat also dries out the pipes and pieces and driving with the leak lowered the heat through the system and the interior of the muffler could have corroded and blocked itself.
Dropping the pipe at each joint is a quick test.

You're welcome. Please let us know what you find.

Okay, with the new symptoms try spraying a bit of starter fluid into the intake, that should give you a direction, if it tries to fire and run on the spray then your issue is likely a fuel pump issue. It could cause both the low power surging and the no start now. Sometime you can get them to work if you give the bottom of the tank a good whack. That would tell you for sure it's a failing pump.

Yep, they can be working and quit while you are driving down the road. They are not hard to test on most vehicles. This isn't for your exact vehicle but gives an idea of the process.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator